Under Title 18 U.S. Code 597, it is a serious federal crime to buy or sell votes. This means using money as an incentive to sway how a person votes or whether they vote. If you are convicted of this crime, you could face up to 2 years in federal prison.

Expenditures to Influence Voting - 18 U.S. Code 597
18 U.S. Code 597 makes it a federal crime to use expenditures to sway someone's vote.
18 U.S.C. 597 says, "Whoever makes or offers to make an expenditure to any person, either to vote or withhold his vote or to vote for or against any candidate; and

Whoever solicits, accepts, or receives any such expenditure in consideration of his vote or the withholding of his vote-

Shall be fined under this title or imprisoned not more than one year, or both; and if the violation was willful, shall be fined under this title or imprisoned not more than two years, or both."